Parevocellular neurosecretory neurons (PINNs) in the paraventricular nucleus of the hypothalamus produce the neuropeptides corticotropin releasing hormone-41 (CRF) and arginine vasopressin (AVP), which serve an essential physiological role in initiating integrating and adaptive responses to stress via regulation of the hypothalamic- pituitary-adrenal (HPA) axis. Although stress is well known to activate CRF and AVP gene expression, the synaptic and transcriptional mechanisms involved remain largely undetermined. The goal of the proposed project is to develop a dissociated hypothalamic cell culture system which can be used to identify synaptically acting factors to model the changes in CRF and AVP gene expression that are observed in PNNs following exposure to stress in vivo, specifically the rapid increase in CRF hnRNA and the delayed induction of AVP hnRNA, and use this in vitro model to elucidate the transriptional mechanisms that operate on the genes. These experiments will contribute significantly to the understanding of the neural mechanisms underlying the stress response and may have potential significance for clinical disorders that involve dysregulation of the HPA axis.